Belt conveyors are used in a wide range of applications for transporting both individual packages and granular material such as grain, ore, gravel, and the like. Such belt conveyors typically comprise a top conveying run on which the load is placed, and a bottom return run. The ends of the belt are connected together by a belt lace or like device to form an endless belt mounted on end rollers at each end of the belt conveyor.
Typically belt conveyors for granular material have outer edges of the belt on the top conveying run raised to form a trough to retain the material on the belt. The top conveying run may be supported in the troughed configuration by rollers or plates, and in many applications, particularly for conveying agricultural products, the conveying run passes through a tube that supports it in the troughed configuration. At the ends of the conveyor, the belt moves to a flat orientation as it passes over the end rollers, and typically the return run is flat and is supported by idler rollers, plate sections or the like spaced at suitable intervals under the conveyor.
The mechanisms used to drive the belt will vary depending on the conveyor length, load, configuration, and like conditions. In a simple configuration, a motor can be used to drive one of the end rollers of the conveyor. Friction between the belt and drive roller causes the belt to move with the surface of the roller. Where increased force is required to drive the belt because of long length, high load, or the like, the return run typically passes through an S-drive mounted under the conveyor. In the S-drive, idler rollers cause the belt to wrap farther around the drive roller, increasing the frictional force between the belt and drive roller and allowing more power to be transferred from the drive roller to the belt.
A typical portable conveyor for agricultural products will be mounted in a frame supported on wheels and include an actuator operative to raise and lower an upper output end of a conveyor tube while the lower intake end stays near the ground to receive agricultural products to be carried up the conveyor and discharged into the top of a grain bin. The lower receiving end typically includes a metal hoppered intake section where the belt runs flat before passing into the tube and moving to the curved orientation inside the tube. In this flat portion the edges of the belt may be curved up somewhat, and there will be a seal strip, typically a stiff rubber strip, fastened along a top edge thereof to the walls of the hopper such that the lower edge thereof bears against the belt and keeps the granular material on the belt.
In belt conveyors for agricultural products, there is also often a hoppered intake portion pivotally attached to the bottom end of the conveyor. This portion is positioned more or less horizontally under the center discharge of a belly dump grain trailer for example. The top run of the belt then must run horizontal to the pivot axis then make an angle upward. The belt is under tension and will therefore tend to rise up at the pivot axis in response to that tension. In order to hold the belt down, it is common to provide an S-roller arrangement again whereby the belt passes from the front end of the hopper rearward over a roller at the pivot axis then forward again to another roller then rearward up the angled main conveyor portion.
A problem arises when conveying oilseeds such as canola or flax. The seeds tend to bounce around and gather under various portions of the belt and under the seal strip where they are crushed. The crushed oilseeds release oil which causes the belt to slip on the drive rollers, and the crushed seeds are very sticky and gummy and build up on the belt and rollers, under the seal strip, and in various other areas under and around the belt, fouling the mechanisms. This crushed gummy buildup must then be scraped off, a very laborious operation. A typical farm may have auger conveyors as well as belt conveyors and so farmers will often choose to use the auger conveyor to avoid contaminating the belt conveyor.